Solar thermal connects to district heating

Date: 1 July 2014

Large-scale solar thermal plants can make European district heating systems more environmentally friendly and they complement combined heat and power perfectly in these times of transition of the energy systems. Around 110 experts in solar thermal energy and district heating from 13 countries met at the 2nd International Solar District Heating Conference on 3 and 4 June 2014 in Hamburg to exchange experiences and discuss common strategies.

With the on-going transition of the energy systems, solar thermal energy is getting more and more attractive to district heating operators. Indeed, the electricity market currently experiences a radical change: since large fractions of solar and wind electricity put pressure on the electricity prices, especially gas combined heat and power plants work at the limit of cost-effectiveness. It is more and more frequently the case that market prices for electricity get lower than the operating cost of the plant, which has then to be shut down. The heat, considered until now an almost free side product from electricity production, is then missing and must be produced at much higher cost by boilers. “At this point, solar thermal energy is the perfect complement as the numerous examples from Denmark show”, says Thomas Pauschinger, board member of the research institute Solites in Stuttgart and co-organizer of the event. Also steady prices and security of supply are current arguments for solar thermal energy. “The more fossil fuels prices on the heating market increase, the more interesting solar thermal gets as alternative”, says John Miller, head of the department of energy politics of the German district heating association AGFW.

At the technical tour, participants had the opportunity to discover a light house solar district heating plant: the “Energy Bunker”. On the roof of a reconverted bunker from WWII, the largest evacuated tube collector plant in Germany with 1 350 m² produces 600 megawatt hour solar thermal energy per year and feeds it in the local district heating net of the city’s energy supplier Hamburg Energie. Near the energy bunker, Hamburg Energie also operates the local heat net Wilhelmsburg Mitte in which several clients can feed-in decentral renewable heat. The energy supplier hosted the conference in its historical buildings of the old waterworks.

Moreover, the speakers of the 2nd International Solar District Heating Conference reported about many international projects, among which in Canada, Chile and of course Denmark. The conference focused on international exchange of technical aspects and political boundary conditions and took place in the frame of the EU project SDHplus, which is additionally supported by the German Ministry for Economic Affairs and Energy.